1. Technical Field
This invention relates in general to carbon nanotube films, fabrics, layers, and articles and in particular to making electrically conductive articles from carbon nanotube films, fabrics, or layers for a variety of uses in circuits or the like.
2. Discussion of Related Art
The reliable fabrication of electrically conductive, ultra-thin metallic layers and electrodes in the sub-10 nm regime is problematic, see, e.g., S. Wolf, Silicon Processing for the VLSI era; Volume 2xe2x80x94Process Integration (Lattice Press, Sunset Beach, 1990). Metal films in this size regime are usually non-continuous and not conductive over macroscopic distances. Furthermore, these sub-10 nm films are prone to thermal damage by electrical current making them unsuitable for applications such as electrical interconnects in semiconductor devices. Thermal damage of thin metal interconnects caused by their low heat conductivities is one of the main factors inhibiting dramatic miniaturization and performance improvements of highly integrated semiconductor devices.
Conventional interconnect technologies have a tendency to suffer from thermal damage and metal diffusion eroding the performance of the semiconductor devices especially from degradation of the electrical properties. These effects become even more pronounced with size reduction in current generation 0.18 um and 0.13 um structures, e.g. by metal diffusion through ultra-thin gate oxide layers.
There is therefore a need in the art for conductive elements that may operate well in contexts having high current densities or in extreme thermal conditions. This includes circuit contexts with very small feature sizes but includes other high current density extreme thermal environment contexts as well. There is also a need for conductive elements that will be less likely to diffuse undesirable amounts of contaminants into other circuit elements.
The invention provides nanotube films and articles and methods of making the same. Under one aspect of the invention, a conductive article includes an aggregate of nanotube segments in which the nanotube segments contact other nanotube segments to define a plurality of conductive pathways along the article.
Under other aspects of the invention, the nanotube segments may be single walled carbon nanotubes, or multi-walled carbon nanotubes. The various segments may have different lengths and may include segments having a length shorter than the length of the article.
The articles so formed may be disposed on substrates, and may form an electrical network of nanotubes within the article itself.
Under other aspects of the invention, conductive articles may be made on a substrate by forming a nanotube fabric on the substrate, and defining a pattern within the fabric in which the pattern corresponds to the conductive article.
Under other aspects of the invention, the nanotube fabric is formed by growing the nanotube fabric on the substrate using a catalyst, for example, in which the catalyst is a gas phase catalyst, or in which the catalyst is a metallic gas phase catalyst.
Under other aspects of the invention, the nanotube fabric is formed by depositing a solution of suspended nanotubes on a substrate. The deposited solution may be spun to create a spin-coating of the solution.
Under other aspects of the invention, the solution may be deposited by dipping the substrate into the solution.
Under other aspects of the invention, the nanotube fabric is formed by spraying an aerosol having nanotubes onto a surface of the substrate.
The invention provides a method of making a film of conductive nanotubes. Under one aspect of the invention a substrate is provided and a vapor-phase catalyst is introduced to foster growth of nanotubes. A carbon source is also introduced to grow a layer of nanotubes that are substantially parallel to a major surface of the substrate.
Under another aspect of the invention, the vapor-phase catalyst is a metallocene.
Under another aspect of the invention, conductive articles are made on a substrate, by forming a nanotube fabric on the substrate; defining a pattern within the fabric in which the pattern corresponds to the conductive article; and removing a portion of the fabric so that the patterned fabric remains on the substrate to form conductive articles.
Under another aspect of the invention, conductive articles are made on a substrate, by providing a substrate, introducing a vapor-phase catalyst to foster growth of nanotubes, and introducing a carbon source to grow a layer of nanotubes that are substantially parallel to a major surface of the substrate.
Under another aspect of the invention, conductive articles are made on a substrate, by providing a substrate; providing a patterned layer of material; providing a catalyst that fosters growth of nanotubes; and providing a carbon source, so as to grow nanotubes substantially parallel to a major surface of the substrate in regions defined by the pattern.
Under another aspect of the invention, the patterned layer of material is an insulator or a semiconductor and wherein the nanotubes grow over the patterned material.
Under another aspect of the invention, the patterned layer is a patterned metal layer and wherein the nanotubes grow in areas other than the patterned metal layer.